Nordost Valhalla vs. SR Atmosphere Euphoria speaker cables

I really need advice on upgrading acoustic cables.
I'm thinking about exchanging Nordost Valhalla & Synergistic Research Galileo Cells cable for SR Atmosphere X Euphoria Level 3 Speaker Cable. Will I get an improvement?
Or go with a SR SX?
I will be grateful for any experience, but only related to these brands.
I’m confused. The atmosphere is a step down from the Galileo. Unsure as to why that should be an improvement
I have Euphoria Level 3 and it is absolutely superb, but have not directly compared with those others. Honestly not even sure if its better than Galileo, or if so by how much. I suspect it is, based solely on the newest generation always out performs the one before. Even when the one before was crazy expensive. If I was between those two I would call and talk directly with Ted.